Tearing crystals apart

Researchers in Japan have measured the van der Waals force between individual layers of the semiconductor gallium selenide in its atomically thin form. The work which saw the scientists tear apart the layers at the bulk level rather than teasing them apart in the transmission electron microscope using double-sided sticky tape. The process involved tearing the crystal layers apart with a tensile testing machine at a rate of 50 micrometers per second. The study provided a baseline measure of interlayer strength in the material which could then be compared to the strength of the same material doped with tellurium. The addition of just 10% tellurium increases its strength sevenfold.